U.S. patent application number 11/885199 was filed with the patent office on 2008-09-25 for lid for a container and a process for making the same.
This patent application is currently assigned to NOSHMELL PTY LTD. Invention is credited to George Leonard Bayss, Nicholas Robert Leonard Bayss.
Application Number | 20080230541 11/885199 |
Document ID | / |
Family ID | 36926973 |
Filed Date | 2008-09-25 |
United States Patent
Application |
20080230541 |
Kind Code |
A1 |
Bayss; George Leonard ; et
al. |
September 25, 2008 |
Lid for a Container and a Process for Making the Same
Abstract
A lid (2) for a container (67), the lid (2) comprising a first
plastic layer (15) including a portion having at least one colored
pigment and a second plastic layer (14) including at least one
thermochromic substance capable of becoming translucent upon
reaching a predetermined temperature in response to heat transfer
from or to contents of the container so as to reveal the colored
pigment of the first layer. Alternatively, there is described a lid
comprising a layer with a portion (62,63) that becomes either
observable or non-observable at the predetermined temperature.
Inventors: |
Bayss; George Leonard; (New
South Wales, AU) ; Bayss; Nicholas Robert Leonard;
(New South Wales, AU) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER, EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
NOSHMELL PTY LTD
BONDI JUNCTION, NSW
AU
|
Family ID: |
36926973 |
Appl. No.: |
11/885199 |
Filed: |
February 27, 2006 |
PCT Filed: |
February 27, 2006 |
PCT NO: |
PCT/AU2006/000251 |
371 Date: |
May 14, 2008 |
Current U.S.
Class: |
220/200 ;
156/244.11 |
Current CPC
Class: |
B65D 2543/00092
20130101; B65D 2203/12 20130101; B65D 2543/00296 20130101; B65D
43/0202 20130101; B65D 2543/00314 20130101; B65D 2543/00537
20130101 |
Class at
Publication: |
220/200 ;
156/244.11 |
International
Class: |
B65D 43/00 20060101
B65D043/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2005 |
AU |
2005900906 |
Claims
1. A lid for a container, the lid comprising a first plastic layer
and a second plastic layer disposed on top of the first layer, the
first layer including at least one portion comprising at least one
coloured pigment, the second layer including at least one portion
comprising at least one thermochromic substance which is capable of
becoming substantially translucent upon reaching a predetermined
temperature in response to heat transfer from or to contents of the
container so as to reveal at least one of the portions comprising
the coloured pigment of the first layer.
2. A lid for a container, the lid comprising a first HIPS layer and
a second HIPS layer disposed on top of the first layer, the first
layer comprising at least one portion having at least one coloured
pigment, the second layer including at least one portion having at
least one thermochromic substance in an amount up to 12 wt % of the
layer and having a reduced particle size, which thermochromic
substance is capable of becoming substantially translucent upon
reaching a predetermined temperature in response to heat transfer
from or to contents of the container so as to reveal at least one
of the portions comprising the coloured pigment of the first layer,
the second layer having a thickness substantially less than the
thickness of the first layer.
3. A lid according to claim 1 including one or more additional
plastic layer(s).
4. A lid according to claim 3 wherein the additional plastic
layer(s) include one or more of coloured pigment(s), thermochromic
substance(s) or regrind.
5. A lid according to claim 1 for a hot or cold cup or
container.
6. A lid according to claim 1 wherein each layer of the lid ranges
from about 100 .mu.m up to about 400 .mu.m thickness, with the
total thickness of the lid for a two layer lid in the range of 200
.mu.m to about 800 .mu.m.
7. A lid according to claim 1 wherein the second layer is an upper
layer of the lid and the first layer is a lower layer of the lid
and additional plastic layers are positioned below the first
layer.
8. A lid according to claim 1 wherein the second layer is an upper
layer of the lid and the first layer is a lower layer of the lid
and an additional plastic layer(s) includes a thermochromic
material and is positioned above the second layer.
9. A lid according to claim 7 wherein the upper layer of the lid is
about 15% to about 50% of the total lid thickness.
10. A lid according to claim 1 wherein the portion of thermochromic
substance and coloured pigment in each layer is substantially all
of the lid or one or more smaller portion(s) of the lid provided
that at least one of the portions of the second layer must
sufficiently cover a portion of the first layer so as to reveal
that portion at the predetermined temperature.
11. A lid according to claim 1 wherein the first layer includes
regrind of the lid or regrind of a different lid.
12. A lid according to claim 1 wherein the thermochromic substance
has a reduced particle size and is selected from the group
consisting of Matsui Chromicolor BW Grade or PS Conc.
13. A lid according to claim 1 wherein the coloured pigment of the
first layer is such that the first layer is opaque at both the
predetermined temperature and a temperature other than the
predetermined temperature.
14. A lid according to claim 1 wherein the coloured pigment is a
standard pigment dye other than a white pigment or is a standard
pigment dye combined with a white pigment.
15. A lid according to claim 1 wherein the coloured pigment is
added in an add-on rate of about 1 to about 4 wt %.
16. A lid according to claim 1 wherein the thermochromic substance
is included in an amount of about 6 wt % to about 10 wt %.
17. A lid according to claim 1, wherein the colour of the
thermochromic substance and the coloured pigment in each layer is
selected so that a colour or combination of colours which results
is an observable colour at the temperature other than the
predetermined temperature and which colour is distinguishable from
the colour of the lid at the predetermined temperature.
18. A lid according to claim 1, wherein the portion which is
revealed forms a word, symbol, logo, picture or pattern.
19. A lid according to claim 1, wherein the colour change of the
thermochromic substance is reversible, quasi-reversible or
non-reversible.
20. A lid according to claim 1, wherein there is more than one
predetermined temperature.
21. A lid according to claim 1, wherein the predetermined
temperature is a predetermined non-ambient temperature selected
from a predetermined heated non-ambient temperature above about
25.degree. C. or a predetermined cooled non-ambient temperature
below about 25.degree. C.
22. A lid for a container according to claim 1, wherein the lid is
a coffee cup lid and the thermochromic substance is capable of
becoming substantially translucent upon reaching a predetermined
temperature in response to heat transfer from the contents of the
container.
23. A lid for a container, the lid comprising a layer comprising at
least one portion having at least one thermochromic substance which
is adapted to change colour and/or become substantially translucent
upon reaching a predetermined temperature(s) in response to heat
transfer from or to contents of the container, the layer being
provided in at least one portion with at least one coloured
pigment, which portion is observable at said predetermined
temperature(s) and non-observable at a temperature other than the
predetermined temperature(s), the colour of said pigment being the
same or substantially the same colour as that of said thermochromic
substance at a temperature other than the predetermined
temperature(s) or which portion becomes non-observable at said
predetermined temperature(s) and observable at a temperature other
than the predetermined temperature(s), the colour of said pigment
being the same or substantially the same colour as that of said
thermochromic substance at the predetermined temperature(s).
24. A lid according to claim 23 wherein the observable portion
forms a word, symbol, a logo, pattern or picture.
25. (canceled)
26. A process for preparing a lid for a container comprising:
co-extruding a first plastic layer and a second plastic layer, and
optionally one or more additional plastic layers, the first layer
comprising in at least one portion at least one coloured pigment,
the second layer comprising at least one portion comprising at
least one thermochromic substance which is adapted to become
substantially translucent upon reaching a predetermined temperature
in response to heat transfer from or to contents of the container
to reveal at least one of the portions having the coloured pigment
of the first layer.
27. A lid according to claim 1 wherein regrind is added to one or
more layers of the lid.
28. A lid for a container, the lid comprising a first plastic layer
and a second plastic layer disposed on top of the first layer and
optionally one or more additional plastic layers, the first layer
including at least one portion comprising at least one coloured
pigment, the second layer including at least one portion comprising
at least one thermochromic substance which is capable of becoming
substantially translucent upon reaching a predetermined temperature
in response to heat transfer from or to contents of the container
so as to reveal at least one of the portions comprising the
coloured pigment of the first layer, wherein one or more of the
layers of the lid include regrind.
Description
TECHNICAL FIELD
[0001] The present invention relates to a lid for a container and
to a process for making the lid.
BACKGROUND OF THE INVENTION
[0002] Lids for containers are generally known. For example, lids
for disposable beverage containers, such as foam or paper cups, are
known. Such containers are generally used for containing heated
beverages such as tea, coffee or hot chocolate, or for containing
cold or chilled beverages such as soft drinks, juice or water.
[0003] It is known to provide lids with small printed or embossed
warning signs such as HOT or COLD on top of the lids to indicate
that the contents contained in the container are hot or cold,
respectively. However, such embossing or printing does not provide
a true indication of the actual temperature of the contents of the
container.
[0004] In order to provide an indication of the actual temperature,
it is known to provide coextruded (two layered) thermochromic
beverage lids in which one of the layers of the lids contain a
thermochromic substance, such as a thermochromic pigment which
changes under the application of heat or cooling to provide an
indication of the temperature of materials contained in a container
contained by the lid and indicate when the contained material is
too hot or too cold for handling or safe consumption. One example
of such a lid is described in PCT/AU02/00029 by the present
applicants', which is incorporated herein by reference. However,
such lids suffer from a number of disadvantages.
[0005] One disadvantage is that, unlike the use of thermochromic
materials in plastic drink bottles, spoons and containers which
have relatively thick substrates and where the use of thermochromic
substances is relatively straightforward, hot container lids, such
as coffee cup lids, are composed of thin substrates of the order of
less than 1 mm, more particularly of the order of less than 0.5 mm
and typically of 100 to 400 .mu.m thickness; accordingly the
properties of the lid by inclusion of thermochromic materials by
conventional means are compromised.
[0006] Another disadvantage is that significant amounts of
thermochromic material must be added to produce a desired colour
coverage. Standard pigment dyes can be added to lids to produce a
desired colour by well known processes, with the standard dye in a
capsulated form added to the masterbatch with minimal add rates
(2-3%). When a thermochromic dye is used however, in order to
achieve the desired and effective colour, add rates in excess of
12% are typically required for thin substrates such as lids (lower
add rates of 3% to 4% of thermochromic can effectively be used with
thick substrates but such add rates are not suitable for use with
lids). Further, when not enough thermochromic material is added,
the resulting colour is insufficient in density and it is necessary
to increase the add rate even further in order to produce a denser
colour. The use of add rates in excess of 12% compromises the
structural integrity of the lid because typical thermochromic dyes
naturally have an enlarged particle size compared to standard dye
pigments. Also some lids are formed from high impact polystyrene
which contains a rubber component to allow the lid to be flexible
and suited for hot beverage container lids. The particle size of
the thermochromic particles causes a loss of lid flexibility and
lids become brittle and have a tendency to tear and thus are
unsuitable for the application for which they are intended
[0007] A further disadvantage is with translucency. Because lids
are typically formed from thin substrates of the order of less than
1 mm in thickness and because the lids include in excess of 10-12%
of the thermochromic substance in order to achieve the desired
colour result, whilst the lid may display the appropriate colour in
a "cold state", on heating such lids to a hot state the lids become
translucent with no actual defined colour present. This is because
the nature of thermochromic substances is that when the
thermochromic substance changes from its cold ambient colour under
heat, the first colour disappears to an almost clear translucent
state with only a pale light colouring. The problem with
translucency is not improved by adding higher add on rates of up to
20% of the thermochromic substance which makes no difference to the
translucency of the lids and which, in view of the high volume of
the enlarged particles of the thermochromic material in the thin
substrate adversely affects and weakens the structural integrity of
the lid resulting in lids that are brittle and which tear/crack
easily and which are not durable, flexible or bendable. In addition
such lids may show pitting or holes from exploding thermochromic
particles during manufacture. Such pitting or holes compromise both
the strength and flexibility of the lid and are visually
undesirable.
[0008] The problem of translucency is exacerbated by the inclusion
of regrind from off-cuts recycled in the bottom of the lid layers
which regrind may be included as a standard step in lid manufacture
as a cost-cutting measure. When a thermochromic substance is
applied to a top layer of a lid and regrind is included as a bottom
layer, and the lid is heated to the hot state, the colour change
results in both layers resulting in loss of colour and translucency
in both layers. This is particularly evident when high impact
polystyrene (HIPS), which is inherently translucent, is used as the
layers of the lid. High impact polystyrene is the most dominant
material used to make lids such as hot beverage lids because it has
a rubber content which aids in durability and flexability. HIPS is
also a cost efficient material and differs from other raw plastic
materials, such as poly(phenylenesulphide) (PPS), which are too
brittle for cup lids.
[0009] To minimise translucency, products using thermochromic
materials typically rely on a secondary underlying colour to
communicate a desired end colour. However, such steps are not
successful in application to the thin substrates of lids. For
example, most products employ a thermochromic micro-encapsulated
dye in which a secondary underlying colour is infused within the
capsule. However, HIPS used to manufacture lids, as provided
commercially, is opaque and slightly translucent. In this regard
HIPS is naturally a cloudy off white colour (which may be grey when
regrind is included) and the white pigment is typically added to
the mix on making lids in order to prevent the lids from becoming
transparent. However, the pigment detrimentally affects the
thermochromic colouring ability by adverse colour mixing in the
layer and through light refraction. For example when a blue to red
colour change is desired, the cold (ambient) state will present the
appropriate cold blue colour but in the hot state, instead of the
desired red, a translucent pink colouring results because the
thermochromic substances do not change to a distinct deep colour.
Instead a pale semi-clear colour, lighter than the cold colour
results, and the natural off-white pigment of HIPS mixes with the
pale colour to make the resulting colour even paler. This result is
undesirable and results in a confusing colour change such that a
user can almost see into the cup when it is in the hot state and
the colour of the liquid in the cup (for example coffee or tea) can
alter what the user actually sees as the hot colour.
[0010] Another disadvantage is that on the lid becoming
translucent, condensation from the contents contained in the cup
may attach to the underside surface of the lid making the
semi-translucent lid even more translucent in the parts where the
condensation is attached.
[0011] An example of an existing product in the market place that
has failed to overcome this translucency problem is thermochromic
straws. These straws work by contact of the straw with a cold
beverage which results in a change in the colour of the straw.
Thermochromic straws are thin by nature and do not have a distinct
cold (ambient) colour. On cooling with contact of the beverage, the
colour seems to disappear and no real new colour becomes apparent.
The colour is more the colour of the liquid being sucked up the
straw than any other colour.
[0012] The problems referred to above are not solved by using
mono-layer lids. A mono-layer lid is produced as a single layer
from one film of plastic and the layer is thicker than layers
making up multi-layered lids. With a mono-layer lid, thermochromic
material needs to be applied to the entire thickness of the layer
of the lid and significant amounts of thermochromic material needs
to be applied so as to achieve a sufficiently dense colour.
Therefore the cost of producing a mono-layer lid is substantial and
not commercially viable. The cost of producing a mono-layer lid
including a thermochromic material may be 5 to 10 times that of
producing a multi-layered lid where thermochromic material is
included in only one of the layers.
[0013] There is a need for methods for making thermochromic lids in
a commercially viable manner such that a distinct colour results in
both the ambient and heated and cooled states.
OBJECT OF THE INVENTION
[0014] It is an object of the present invention to overcome or
substantially ameliorate at least one of the above disadvantages or
to provide a suitable alternative.
SUMMARY OF THE INVENTION
[0015] According to a first aspect of the invention, there is
provided a lid for a container, the lid comprising a first plastic
layer and a second plastic layer disposed on top of the first
layer, the first layer including at least one portion comprising at
least one coloured pigment, the second layer including at least one
portion comprising at least one thermochromic substance which is
capable of becoming substantially translucent upon reaching a
predetermined temperature in response to heat transfer from or to
contents of the container so as to reveal at least one of the
portions comprising the coloured pigment of the first layer.
[0016] According to a second aspect of the invention, there is
provided a lid for a container, the lid comprising a first HIPS
layer and a second HIPS layer disposed on top of the first layer,
the first layer comprising at least one portion having at least one
coloured pigment, the second layer including at least one portion
having at least one thermochromic substance in an amount up to 12wt
% of the layer and having a reduced particle size, which
thermochromic substance is capable of becoming substantially
translucent upon reaching a predetermined temperature in response
to heat transfer from or to contents of the container so as to
reveal at least one of the portions comprising the coloured pigment
of the first layer, the second layer having a thickness
substantially less than the thickness of the first layer.
[0017] According to another aspect, there is provided a lid for a
container, the lid comprising a layer comprising at least one
portion having at least one thermochromic substance which is
adapted to change colour and/or become substantially translucent
upon reaching a predetermined temperature(s) in response to heat
transfer from or to contents of the container, the layer being
provided in at least one portion with at least one coloured
pigment, which portion is observable at said predetermined
temperature(s) and non-observable at a temperature other than the
predetermined temperature(s), the colour of said pigment being the
same or substantially the same colour as that of said thermochromic
substance at a temperature other than the predetermined
temperature(s) or which portion becomes non-observable at said
predetermined temperature(s) and observable at a temperature other
than the predetermined temperature(s), the colour of said pigment
being the same or substantially the same colour as that of said
thermochromic substance at the predetermined temperature(s).
[0018] According to another aspect of the invention, there is
provided a process for preparing a lid for a container
comprising:
[0019] co-extruding a first plastic layer and a second plastic
layer and optionally one or more additional plastic layers, the
first layer comprising in at least one portion at least one
coloured pigment, the second layer comprising at least one portion
comprising at least one thermochromic substance which is adapted to
become substantially translucent upon reaching a predetermined
temperature in response to heat transfer from or to contents of the
container to reveal at least one of the portions having the
coloured pigment of the first layer.
Definitions
[0020] The following definitions are intended as general
definitions and should in no way limit the scope of the present
invention to those terms alone, but are put forth for a better
understanding of the following description.
[0021] Unless the context requires otherwise or specifically stated
to the contrary, integers, steps, or elements of the invention
recited herein as singular integers, steps or elements clearly
encompass both singular and plural forms of the recited integers,
steps or elements.
[0022] Throughout this specification, unless the context requires
otherwise, the word "comprise", or variations such as "comprises"
or "comprising", will be understood to imply the inclusion of a
stated step or element or integer or group of steps or elements or
integers, but not the exclusion of any other step or element or
integer or group of elements or integers. Thus, in the context of
this specification, the term "comprising" means "including
principally, but not necessarily solely".
[0023] Those skilled in the art will appreciate that the invention
described herein is susceptible to variations and modifications
other than those specifically described. It is to be understood
that the invention includes all such variations and modifications.
The invention also includes all of the steps, features,
compositions and compounds referred to or indicated in this
specification, individually or collectively, and any and all
combinations or any two or more of said steps or features.
[0024] All the references cited in this application are
specifically incorporated by reference are incorporated herein in
their entirety. Inclusion herein of any given reference is not
intended to indicate that the reference is generally known in
Australia or elsewhere.
[0025] By "plastic" is meant any synthetic or natural organic
material which may be shaped when soft and then hardened such as
resins, resinoids, polymers, cellulose derivatives, casein
materials and proteins.
[0026] By "ambient temperature" is meant the room temperature of
the environment in which the lid is situated.
[0027] By "substantially translucent" means that the thermochromic
material is capable of allowing light to pass therethrough but
diffusing it so that objects on the other side cannot be clearly
distinguished. The material however may not become totally
transparent and may retain some colour.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Preferred embodiments of the invention will now be
described, by way of example only, with reference to the
accompanying drawings in which:
[0029] FIG. 1 is a partial perspective view of a lid in accordance
with one embodiment of the present invention and a container;
[0030] FIG. 2 is a perspective view of the lid of FIG. 1 including
a cut away section showing the cross-section of the layers of the
lid;
[0031] FIG. 3 shows the cross-section of the cut away section of
the lid of FIG. 2 in more detail;
[0032] FIG. 4 shows the cross-section of the cut away section of
another lid of a less desirable embodiment of the invention in
which condensation occurs on the inner surface of the lid;
[0033] FIG. 5 is a perspective view of another lid in accordance
with a less desirable embodiment of the invention including a cut
away section showing a cross-section of the layers of the lid and
in which pitting is shown on the surface;
[0034] FIG. 6 shows the cross-section of the cut away section of
the lid of FIG. 5 in more detail;
[0035] FIG. 7 shows the cross-section of a cut away section of a
lid in accordance with another embodiment of the invention; and
[0036] FIGS. 7A and 7B show perspective views of the lid in
accordance with FIG. 7 at ambient temperature (FIG. 7A) and at a
predetermined non-ambient temperature (FIG. 7B).
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0037] There is disclosed herein a lid for a container, the lid
comprising a first plastic layer and a second plastic layer
disposed on top of the first layer, the first layer comprising at
least one portion having a coloured pigment, the second layer
comprising at least one portion having at least one thermochromic
substance which is capable of becoming substantially translucent
upon reaching a predetermined temperature in response to heat
transfer from or to contents of the container and reveal at least
one of the portions having the coloured pigment of the first
layer.
[0038] The lid may optionally include additional plastic layers
i.e., the lid may comprise two or more layers. For example, the lid
may be formed from two, three, four, or more layers. When more than
two layers are used at least one layer is the first layer and at
least one layer is the second layer and the additional layers are
suitably positioned below the first layer. The additional layer(s)
may include a coloured pigment and/or regrind. For example the
additional layer(s) may be a darkened layer, which by virtue of
light refraction will cause the first layer to appear darker. Using
additional darkened layers may decrease light refraction between
the layers, thereby enabling less thermochromic material to be used
which may make the lid more economically viable to manufacture.
[0039] The lid of the present invention may be for a hot or cold
cup or container and may be for a lid for a beverage cup or
container, such as a disposable beverage container for containing a
hot or cold substance such as heated or chilled beverage (coffee,
tea, hot chocolate, iced chocolate, soft drink, soup, food or
foodstuff, although this list is by no means comprehensive). The
lid may be for use with foam, polystyrene or paper cups commonly
used in the sale of heated or chilled beverages such as coffee. In
this regard with heated beverages, it is the heat (or steam) from
the beverage which suitably effects the change in the thermochromic
material and thereby the colour of the lid such that one can
identify whether the beverage is at a desired temperature or is to
hot to drink. With chilled beverages, the proximity of the cold
liquid to the lid or the actual contact of the cold liquid with the
lid may effect a change in colour of the thermochromic material and
thereby the colour of the lid so that one can determine if the
drink is cold enough or is being served or stored at a desired
temperature. Also, the change in colour may be effected by placing
the lid in a heated or chilled environment such as in an oven or
refrigerator.
[0040] The layers of the lid may be in the form of thin substrates
of the order of micron to millimeter thickness. Typically each
layer of the lid may range from about 100 .mu.m up to about 400
.mu.m thickness, with the total thickness of the lid for a two
layer lid being of the order of about 200 .mu.m to about 800 .mu.m
. The thickness of the lid is largely determined by the process of
manufacture and equipment used and whether a thicker, sturdier
high-quality lid or a cheaper, thinner lid is desired for the end
application. For example the total thickness of a lid in accordance
with one embodiment of the invention may be of the order of about
0.3 to about 0.4 mm (about 300 to about 400 .mu.m).
[0041] The second layer is suitably an upper layer of the lid. The
first layer is suitably a lower layer of the lid which, in the
absence of additional plastic layers, is in direct contact with any
heat from a substance contained in the container. The upper layer
of the lid containing the thermochromic material may be suitably
substantially thinner than the lower layer. For example, the upper
layer of the lid may be about 15% to about 50%, about 20% to about
40% or about 25% to about 30% of the total lid thickness. In one
embodiment the upper layer of the lid may range in thickness from
about 120 .mu.m to about 160 .mu.m and the lower or bottom layer of
the lid may range from about 180 .mu.m to about 240 .mu.m.
[0042] The portion of thennochromic substance and coloured pigment
in each layer may be substantially all of the lid or one or more
smaller portion(s) of the lid. The portion of the upper layer need
not necessarily be the same size as the portion of the lower layer,
however at least one of the portions of the upper layer must
sufficiently cover a portion of the lower layer so as to reveal
that portion at the predetermined temperature.
[0043] The lid is formed from a plastics material. In one
embodiment the lid is suitably made from high impact polystyrene
(HIPS). The lid may be in the form of a co-extruded outer and inner
layer. The portion(s) having the translucent properties may be only
in the outer layer. The inner layer may comprise regrind of a lid
of the present invention or a regrind of a different lid.
[0044] In various embodiments additional plastic layers may also be
present.
[0045] With respect to regrind, manufacturing of lids typically
generate excess material referred to as "webbing". Webbing is
recycled in a process called regrind. Regrind is used because
thermochromic materials are expensive and adding a portion of the
regrind may lower the cost of manufacturing the lid. Typically
regrind is added to the first or lower layer (which may be the
bottom or base layer adjacent the contents of the container) of the
lid. Regrind is typically not added to the upper layer as the
regrind may discolour the thermochromic pigment. For example with
HIPS which typically includes a white pigment, the regrind may
cause the HIPS to become grey with loss of sheen. The
discolouration of the regrind pigment may also create a denser
colour affect on the colour of the lid at a temperature other than
the predetermined temperature and allow a reduction in the add rate
of the thermochromic material in the upper or second layer.
However, in certain embodiments a small percentage of regrind may
be added to the upper layer so as to provide an opportunity to use
excess regrind stockpiles (which may occur) and/or to add depth to
the colour of the lid at a temperature not being the predetermined
temperature.
[0046] By inclusion of regrind in the first layer, the first layer
may thereby contain thermochromic substance together with a
coloured pigment from the regrind. Where a different lid is used as
regrind, it may be desirable to use one having a thermochromic
material having a reduced particle size such as BW Grade or PS
Conc. available from Matsui International, although the invention
is not limited to such regrinds and regrinds having no
thermochromic material or containing standard thermochromic
materials of conventional particle size may be used.
[0047] Typically the coloured pigment of the first layer is chosen
so that the first layer is opaque at both the predetermined
temperature and a temperature other than the predetermined
temperature so as to provide a dense colour. The coloured pigment
may be any standard pigment dye other than a white pigment,
although the first layer may additionally contain a white pigment.
Suitably the coloured pigment is added in an add-on rate of about 2
to about 3 wt %. The pigment may be chosen to be the colour of the
desired colour at the predetermined temperature. For example, the
first layer may contain a red pigment so that the colour of the lid
at the predetermined temperature is red. Standard colour may also
be added to the first layer via regrind, and consequently the total
add on rate of the standard pigment may be in the range of about 1
to about 4 wt %. The amount of pigment that is added may differ
depending on the desired colour. For example less pigment may be
added when the pigment is black than when the pigment is blue.
[0048] A standard pigment dye is suitably chosen for the first
layer as when the thermochromic material becomes substantially
translucent at the predetermined temperature, the standard pigment
dye in this layer is observable as a distinct colour. When HIPS is
used in the second layer, due to the nature of the HIPS also being
mostly translucent, at the predetermined temperature the standard
pigment dye of the bottom layer is observable and if this pigment
is red, the lid will be a distinct red colour at the predetermined
temperature. The red in the bottom layer may thereby prevent the
bottom layer from becoming translucent at the predetermined
temperature. Further by inclusion of the standard pigment, a denser
colour may be provided to the lid at a temperature other than the
predetermined temperature.
[0049] The thermochromic material in the upper layer may be used in
the absence of any other coloured pigments aside from any
underlying colour contained within the thermochromic material
itself. Materials having thermochromic properties, including but
not limited to thermochromic pigments, are known. The thermochromic
material is chosen such that it is only visible when the
temperature is other than the predetermined temperature. For
example, in one embodiment, the thermochromic material in the
second layer is visible when the lid is at a temperature other than
the predetermined temperature but becomes substantially translucent
at the predetermined temperature. The translucent colour change may
be gradual from near the predetermined temperature and complete by
the predetermined temperature. In this regard the effect of heating
or cooling may not result in total translucency. Rather the colour
may change in the upper layer from a dark solid colour to a
different much paler colour which by light refraction mixes with
the standard, non-colour changing pigment in the bottom layer, the
colour of the standard pigment completely dominating the
thermochromic material at the predetermined temperature. Whilst it
would appear that the upper layer has become totally translucent it
may in fact be a pale see-through colour (for example for a lid
changing from a dark brown to red, the layer including the
thermochromic material may be a very pale pinky/red colour).
[0050] The material having thermochromic properties may be a
thermochromic pigment, resin or the like. The thermochromic
material may be chosen such that it has a reduced particle size in
comparison with conventional thermochromic materials. The present
inventors have found that thermochromic materials having a reduced
particle size are desirable for use in the thin plastic layers of
the lid.
[0051] Thermochromic pigments are available from several sources,
for example, those denoted F4, G7 or J8 sold under the trademark
CHROMICOLOR by Matsui International Co., Inc. of Gardena, Calif.,
United States of America. The thermochromic material may be
included in the second plastic layer in add rates of less than
about 12 wt %, for example less than about 10 wt % or less than 5
wt %.
[0052] The thennochromic material may be included in the second
plastic layer in an amount of about 6 wt % to about 10 wt %. Lower
add on rates may be beneficial in terms of costs of manufacture and
the high cost of the raw materials. Use of above about 12 wt % of
the thermochromic material results in a lid which is less
economically viable and the structural integrity of the lid may be
compromised such that it tears easily as a result of its
brittleness and is more susceptible to pitting during
production.
[0053] Whilst standard thermochromic materials can be used, in one
embodiment the thermochromic material is a concentrate such as
Matsui Chromocolor BW Grade available from Matsui International
Inc., Gardena, Calif., USA. This product has a reduced particle
size relative to conventional thermochromic materials and has been
the subject of migration and food safety testing and approved by
FDA and other Food Safety Bodies in August 2004 for use in a food
contact situation. Other thermochromic materials may be standard
thermochromic materials altered to reduce their particle size by
the thermochromic material manufacturer, for example Matsui PS Conc
and other microencapsulated masterbatches. In one embodiment the
thermochromic material used in the second (upper) layer is suitably
fresh or virgin material and not material from regrind.
[0054] In one embodiment the thermochromic substance and the
coloured pigment are chosen so that, in combination, the layers
present one observable colour at a temperature other than the
predetermined temperature. Colour mixing may occur in the first
layer as a result of any regrind present containing thermochromic
material which mixes with the coloured pigment and also as a result
of the slight effect of the opaqueness of the HIPS when used. It is
the combination of this colour mixing in the first layer and light
refraction through the layers which results in the overall
observable colour of the lid. The colour of the first layer
contributes to the colour of the lid at a temperature other than
the predetermined temperature because of the translucent nature of
the layer containing the thermochromic material.
[0055] In one embodiment the extent of the colour change may be
affected by the coverage of any dark colour (which may be the
pigment colour contained in the thermochromic material) which
differs from a second distinguishable colour (which is the colour
of the coloured pigment in the first layer) at the predetermined
temperature and different from the observable colour at the
temperature other than the predetermined temperature. This affect
may occur when the first (lower) layer also includes a
thermochromic material in combination with the standard pigment, as
the presence of the thermochromic material may lead to a
discolouration/alteration of the final colour of the first layer
which discolouration is observable through the second (upper layer)
due to the thinness of the second layer i.e., the colour of the
lower layer can be seen through the top layer. This discolouration
may be further compounded by the fact that standard dyes are much
stronger than thermochromic dyes. For example when a blue
thermochromic is placed in an upper layer of the lid with a
standard red pigment in the lower layer, the result is a lid which
has the desired colour at the predetermined temperature (red) but
the discolouration of the observable colour at for example, ambient
temperature results in the ambient colour being only slightly
darker than the hot colour eg., a reddy-purple colour and there is
practically no colour contrast between the hot and ambient states.
Accordingly, the colour of the thermochromic additives and coloured
pigment in each layer may suitably be selected so that a colour or
combination of colours which results is an observable colour at the
temperature other than the predetermined temperature and which
colour is distinguishable from the colour of the lid at the
predetermined temperature.
[0056] As an example, the observable colour of the lid at a
temperature other than the predetermined temperature such as at
ambient temperature may be dark brown/black and the colour at the
predetermined temperature may be bright red. This may be achieved
using a mixture of green thermochromic and turquoise thermochromic
in the second (upper) layer which, by means of light refraction,
can show an observable dark brown/black colour at the temperature
other than the predetermined temperature when a standard red dye is
used (together with any thermochromic from regrind but in the
absence of any white pigment) in the first or lower layer. On
heating or cooling, the lid will present the bright red colour at
the predetermined temperature.
[0057] As another example the observable colour of the lid at a
temperature other than the predetermined temperature may be black
and the colour at the predetermined temperature may be green. This
may be achieved by using a mixture of black thermochromic and
gold/orange thermochromic in the second or upper layer which, by
means of light refraction, can show an observable dark black cold
colour at the temperature other than the predetermined temperature
such as at ambient temperature when a mixture of standard green and
white dyes are used (together with any thermochromic from regrind)
in the first or lower layer. On heating or cooling, the lid will
present a green colour at the predetermined temperature.
[0058] As another example the observable colour of the lid at a
temperature other than the predetermined temperature such as at
ambient temperature may be red and colour of the lid at the
predetermined temperature may be yellow. This may be achieved by
using pink thermochromic in the second or upper layer which, by
means of light refraction, can show an observable dark red cold
colour at the temperature other than the predetermined temperature
when a mixture of standard yellow and white dyes are used (together
with any thermochromic from regrind) in the first or lower
layer.
[0059] In use, with the addition of heat or cooling to the
predetermined temperature, the colour of the second (upper) layer
containing the thermochromic material may disappear and the colour
of the pigment added to at least one portion of the first (bottom)
layer may become visible. The portion which becomes visible may
form words, symbols or patterns against the remainder of the lid
when the contents are at the predetermined temperature.
[0060] The thermochromic material may be capable of returning to
its original colour in response to the temperature of the regions
falling below the predetermined temperature.
[0061] In one embodiment different portions of the lid may contain
different thermochromic materials. For example the lid may include
at least two regions having different thermochromic properties
which are each capable of changing upon reaching differing
predetermined temperatures in response to heat transfer from or to
the contents of the container. In another embodiment three, four or
more regions may be provided. The thermochromic material(s) used
may also be quasi-reversible and allow two or more colour changes.
For example a thermochromic pigment may be blue at one temperature
(such as ambient temperature), red at a different temperature (such
as a temperature of about 45.degree. C.) and yellow at another
temperature (such as a temperature of about 60.degree. C.).
[0062] It is therefore clear from the above that it is possible to
use two or more colours and more than two layers, and where more
than two layers are used, with the addition of different or the
same thermochromic materials in each layer having varying or
similar colour changing temperatures. It is possible to select a
particular combination of colour(s) to indicate most desired
temperatures. One possible use of the lid is one with a safe cold
colour (such as blue), a colour which indicates that the beverage
is at the right temperature to drink (such as orange), and a third
colour (such as red) which indicates that the beverage is too
hot.
[0063] The predetermined temperature may be a predetermined
non-ambient temperature such as a predetermined heated non-ambient
temperature or a predetermined cooled non-ambient temperature. The
temperature other than the predetermined temperature may be ambient
temperature. In one embodiment the ambient temperature is about
20.degree. C. to about 30.degree. C. The predetermined heated
non-ambient temperature may be above about 25.degree. C., for
example about 30.degree. C., about 35.degree. C., about 40.degree.
C., about 45.degree. C., about 50.degree. C., about 55.degree. C.,
about 60.degree. C., or about 65.degree. C. In alternative
embodiments the temperature may be about 45.degree. C., about
50.degree. C., about 55.degree. C., or about 60.degree. C. The
predetermined cooled non-ambient temperature may be below about
25.degree. C., for example about 20.degree. C., about 15.degree.
C., about 10.degree. C., about 5.degree. C., about 0.degree. C.,
about -5.degree. C., about -10.degree.C., or about -15.degree.
C.
[0064] There is also disclosed herein a lid for a container, the
lid comprising a layer comprising at least one portion having at
least one thermochromic substance which is adapted to change colour
and/or become substantially translucent upon reaching a
predetermined temperature(s) in response to heat transfer from or
to contents of the container, the layer being provided in at least
one portion with a coloured pigment, which portion is observable at
said predetermined temperature(s) and non-observable at a
temperature other than the predetermined temperature(s), the colour
of said pigment being the same or substantially the same colour as
that of said thermochromic substance at a temperature other than
the predetermined temperature(s) or which portion becomes
non-observable at said predetermined temperature(s) and observable
at a temperature other than the predetermined temperature(s), the
colour of said pigment being the same or substantially the same
colour as that of said thermochromic substance at the predetermined
temperature(s).
[0065] In this embodiment, the lid may be one in accordance with
the first aspect of the invention and the layer may be coated on
the second plastic layer or may be located between the first and
second plastic layers.
[0066] In this embodiment, a logo, symbol or writing (such as
branding or advertising) may be made to appear on the top of a lid
which at ambient temperature appears to have no logo, symbol or
writing visible on it. The logo, symbol or writing may be coated by
stamping or impregnating the pigment onto the top of the lid using
a standard regular non-changing ink after the lid is made using a
colour substantially identical or similar to that of the lid at
ambient temperature i.e., the colour may be chosen to be
substantially identical to or similar to the thermochromic
material. In this embodiment, the logo, symbol or writing may be
stamped onto the lid as a standard dye (i.e., one that does not
change colour on top of the lid in a colour that matches the colour
of the thermochromic at a temperature below the predetermined
temperature (such as at ambient temperature) and thus is not
visible below the predetermined temperature but when the lid
changes colour the logo, symbol or writing stays the same colour
and is thereby revealed.
[0067] Alternatively or additionally the logo, symbol or writing
may be formed from a thermochromic material such as a
quasi-reversible or non-reversible thermochromic. More than one
logo, symbol or writing may be present and the logo, symbol or
writing may be revealed at different temperatures. In one
embodiment, when the lid is at a temperature other than the
predetermined temperature, a user cannot see anything on the top of
the lid, however once the lid is put on the cup and heated or
cooled to the predetermined temperature, the thermochromic material
changes colour and becomes clear, revealing the logo, symbol or
writing to the user.
[0068] In one embodiment when using a quasi-reversible
thermochromic material in the lid capable of two colour changes
(for example blue to yellow to red), stamping a logo, symbol or
writing on the top of the lid (or a layer of the lid) with normal
ink that matches the colour at a temperature below the
predetermined temperature i.e. the ambient cold colour (such as
blue), the logo, symbol or writing will be visible at both the red
stage and the yellow stage but not the blue stage. Alternatively by
stamping the logo, symbol or writing in a standard dye that is
yellow, then the logo, symbol or writing will be visible at the
blue stage and the red stage, but not the yellow stage. Similarly
using a standard red dye will result in visibility during the blue
and yellow stage but no visibility of the logo, symbol or writing
during the red stage. In another embodiment, by stamping a logo,
symbol or writing that is made from a thermochromic material that
is capable of becoming substantially translucent on the application
of heat, then when using a quasi-reversible material in the lid as
above, it is possible that when the logo, symbol or writing is
stamped in a blue thermochromic with only one translucent colour
change the change occurring during the red stage, then the logo,
symbol or writing will not be visible during the blue stage, will
be visible during the yellow stage but will not be visible during
the red stage. This offers branding and marketing options as well
as enabling logos, symbols or writing to indicate to consumers that
the beverage is at the right temperature to drink or is too hot.
Another scenario is stamping the lid or a layer of the lid with two
(or more) different types of coloured pigments one or both being a
thermochromic material(s) capable of becoming substantially
translucent at various predetermined temperatures. This allows
different logos to appear/disappear at various temperatures.
[0069] Where more than two layers are used for example in a
multi-layer lid, logos, symbols or writing can be provided in any
or between any layers in any desired variation of logo, symbol or
writing or combination of colours. In this embodiment it is
possible for the logo, symbol or writing to be in the form of a
picture.
[0070] There is also disclosed herein a process for preparing a lid
for a container, the process comprising co-extruding a first
plastic layer, a second plastic layer and optionally one or more
additional plastic layers, the first layer including in at least
one portion a coloured pigment, the second layer including at least
one portion including at least one thermochromic substance which is
adapted to become substantially translucent upon reaching a
predetermined temperature in response to heat transfer from or to
contents of the container to reveal the at least one of the
portions having the coloured pigment of the first layer.
[0071] In one embodiment the lid is thermoformed, with
thermochromic pigments added to molten plastic material such as
HIPS before forming. In one embodiment, a process for producing the
thermochromic regions of the lids involves co-extruding two or more
layers of HIPS from separate drums. The inner layer (ie., that
adjacent to or closest to the contents of the cup in use) of HIPS
may be produced conventionally to which is added a coloured pigment
(other than the normal base pigment of white or grey tone) which
does not change colour under heat or cooling and which provides a
depth of colour to the lid. The inner layer may be formed from
scrap and may include a thermochromic material. The outer layer
(i.e., that remote from the contents of the cup in use) may be
produced from HIPS to which is added a thermochromic pigment in the
absence of any white pigment.
[0072] In one embodiment the lid is formed from a plastics material
in which portions are impregnated or blended where appropriate with
the material having thermochromic properties or with a standard dye
and where appropriate thermochromic from regrind. In various
embodiments no water may be present in the thermochromic material
prior or during addition.
[0073] Referring to the drawings, FIG. 1 shows a beverage container
lid 2 of the present invention which includes a sidewall 2A,
corresponding top wall 2B, a rim or lip 3 for engaging beverage cup
67. Edge 4 flares outwardly and independent from contact with cup
67. Beverage container lid 2 also includes a steam release hole
1.
[0074] FIG. 2 shows the lid of FIG. 1 including a cut out cross
section 5 showing an inner layer 7 and an outer layer 6.
[0075] FIG. 3 shows the cross-section 5 of FIG. 2 in more detail.
It can be seen that FIG. 3 represents a magnified representation of
cut out cross section 5 of a beverage container lid 2A. FIG. 3
includes a top surface 11, a layer 14 which corresponds to outer
layer 6 of FIG. 2, a bottom layer 15 which corresponds to inner
layer 7 of FIG. 2, and bottom surface 13. Region 12 denotes a
bonding area between top layer 14 and bottom layer 15 (a
combination of heat and applied pressure allows the layers to bond
and meld together on contact on exit from a drum). At ambient
temperature the outer surface 11 displays an observable colour
combination of layers 14 and 15 in an unmolested state. For this
purpose the top layer 14 includes virgin High Impact Polystyrene
(HIPs) and at least one thermochromic material and the bottom layer
5 includes virgin HIPs, at least one standard dye pigment and
regrind in the form of recycled material of a like lid. In one
embodiment the standard dye pigment is added in an amount
sufficient to provide an opaque covering of bottom layer 15. In one
embodiment top layer 14 represents a layer between 15-35% of the
entire thickness of the lid 2. In one embodiment the thermochromic
material is a standard thermochromic material suitable for use with
HIPs. In another embodiment the thermochromic material is a
concentrate of a standard thermochromic material having its
particle size reduced as mentioned hereinbefore.
[0076] Suitably layer 14 contains at least about 10 wt %
thermochromic material with the remaining material being the virgin
HIP.
[0077] In use, the lid 2 of the invention is placed on container 67
containing a hot or cold beverage and subjected to thermal
communication from the contents of the container 67 thereby
activating the thermochromic material. The thermochromic material
present in top layer 14 is activated and becomes substantially
translucent at a pre-determined non-ambient temperature to thereby
reveal the underlying colour present in the bottom layer 15.
[0078] In one embodiment layer 14 may also contains regrind
material.
[0079] FIG. 4 shows another cross section 10 of a lid 2 however in
this embodiment the standard dye pigment is insufficient to provide
an opaque coverage of the bottom layer 15. In this regard typically
less than 1 wt % is insufficient and 1 to 3 wt % may be
insufficient however sufficiency is dependent on the strength and
brand of pigment used. Where HIPS is used and a white pigment is
not contained therein, a standard dye contained within the
thermochromic capsule and acting as a secondary colour was
insufficient to provide coverage. In use hot liquid 22 from
beverage cup 67 generates steam 23 causing the activation of the
thermochromic material however because of the insufficient
coverage, the bottom layer 15 itself becomes translucent and
condensation 20 is able to be seen through the lid 2 on the surface
13 of the bottom layer 15.
[0080] FIG. 5 shows a lid 2 however in this embodiment pitting 31
occurs on the lid surface. Layer 14 includes a standard
thermochromic additive suitable for HIP environments. The enlarged
particle size of the thermochromic additive inherent in the
standard material and overcrowding of the thermochromic particles
causes an explosion of the crowded particles because the particles
are unable to retain their natural configuration resulting in
pitting 30 visible on the outer surface 11 of the lid 2. FIG. 6
shows a cross-section of the lid 10 showing this pitting in detail.
The pitting also leads to a loss of rubber content causing
brittleness.
[0081] FIGS. 7, 7A and 7B show a lid 2 having a patterns or logos
62 or 64 on their surface. The patterns or logos 63 are selected to
be a colour combination of upper layer 14 and lower layer 15 in the
cold ambient state and is not observable. When thermochromic
additive is subjected to heat or cooling and becomes translucent,
the visible outer substrate 60 colour becomes the colour of the
standard pigment contained in lower layer 15 but the logo 62
remains the colour combination of both layers in the cold ambient
state and becomes observable as the remaining colour changes to the
secondary underlying colour. The logo may be in the form of a
standard non-changing pigment stamped on the lid or it may be a
quasi-reversible or non-reversible thermochromic material.
[0082] The invention will now be described by reference to the
following examples:
In the following examples all add rates assume that the top layer
of the beverage lid has a thickness being approximately 40% of the
thickness of the lid, and the bottom layer being approximately 60%
of thickness of lid. These thicknesses can vary and when they do so
add rates may vary.
EXAMPLE 1
[0083] To achieve a dark brown to bright red lid.
[0084] 25. Top Layer:
TABLE-US-00001 Chromicolor PS Conc BW Grade Green Type #45 about
10% Chromicolor PS Conc BW Grade Turqoise Blue Type #45 about 5%
Virgin HIPS about 85%
[0085] Bottom Layer:
TABLE-US-00002 Pigment Red 247 about 1.0% Pigment Red 242 about
0.1% Balance (regrind from top layer and virgin hips) about
98.9%
2)
[0086] Top Layer:
TABLE-US-00003 Chromicolor PS Conc BW Grade Green Type #45 about
15% Virgin HIPS about 85%
[0087] Bottom Layer:
TABLE-US-00004 Pigment Red 247 about 1.0% Pigment Red 242 about
0.1% Balance (regrind from top layer and virgin hips) about
98.9%
EXAMPLE 2
[0088] To achieve a Red to bright Yellow lid: 1)
[0089] Top Layer:
TABLE-US-00005 Chromicolor PS Conc BW Grade Pink Type #45 about 15%
Virgin HIPS about 85%
[0090] Bottom Layer:
TABLE-US-00006 Pigment White 6 about 0.06% Pigment Yellow 138 about
0.055% Balance (regrind from top layer and virgin hips) about
99.885%
2)
[0091] Top Layer:
TABLE-US-00007 Chromicolor PS Cone BW Grade about 15% Pink Type #45
Virgin HIPS about 85%
[0092] Bottom Layer:
TABLE-US-00008 Pigment White 6 about 0.03% Pigment Yellow 138 about
0.0275% Balance (regrind from top about 99.9425% layer and virgin
hips)
EXAMPLE 3
[0093] To achieve a Charcoal to Green: 1)
[0094] Top Layer:
TABLE-US-00009 Chromicolor PS Conc BW Grade Fast Black Type #45
about 11% Chromicolor PS Conc BW Grade Gold Orange Type #45 about
4% Virgin HIPS about 85%
[0095] Bottom Layer:
TABLE-US-00010 Pigment White 6 about 0.105% Pigment Green 7 about
0.0275% Balance (regrind from top layer and virgin hips) about
99.8675%
2)
[0096] Top Layer:
TABLE-US-00011 Chromicolor PS Conc BW Grade Fast Black Type #45
about 11% Chromicolor PS Conc BW Grade Gold Orange Type #45 about
4% Virgin HIPS about 85%
[0097] Bottom Layer:
TABLE-US-00012 Pigment White 6 about 0.05% Pigment Green 7 about
0.0015% Pigment Yellow 138 about 0.0125% Balance (regrind from top
layer and virgin hips) about 99.936%
[0098] Lids according to the embodiments described above may have
one or more advantages. For example, the lids may be used in the
case of hot beverages to include a warning that there are hot and
potentially hazardous contents contained therein. The lids may also
provide an improved indication of temperature to persons with
minimal eyesight, numbness of the hands and/or fingers and to
persons in darkened locations.
[0099] Although the invention has been described with reference to
specific examples, it will be appreciated to those skilled in the
art that the invention may be embodied in many other forms.
* * * * *